The invention concerns a cooled mechanical seal with a slide ring rotating with the shaft and a counter ring, non-rotatably mounted in the sealing housing.
The medium to be sealed is itself used to carry away the frictional heat of the slide ring and counter ring in known seals of this type. If the medium is unsuited for such cooling purposes by virtue of its nature or high temperature, a cooling system is provided which conducts a coolant over the slide ring and counter ring, said coolant carrying away the frictional heat and/or the heat given off from the medium to be sealed to the rings. For this purpose, in known sealing methods, the coolant is fed through an external heat exchanger by means of a special pump or by the thermosiphon effect and through the sealing housing in the circuit, or, when the seal is used for pumps, a portion of the output flow is tapped on the high-pressure side, cooled in a heat exchanger and fed into the sealing housing, whence it flows to the low-pressure side of the pump to be sealed.
The heat exchanger, mounted separately from the seal, and with which filters, separators and shutoff valves are associated in addition to the necessary connecting pipes, complicate the incorporation of the mechanical seal and in the event of incorect attendance can lead to inability of the seal to function. For this reason separately mounted heat exchangers should not be used with such mechanical seals, which are installed in so-called "Usus" pumps (in German: unabhangige Sicherheitsund Sabotagepumpen = (independent safety and sabotage pumps), which are provided for emergency purposes in nuclear power plants.